1. Field of the Invention
The present invention relates to functional devices suitable as, for example, dye-sensitized solar cells.
2. Description of the Related Art
Functional devices include wet devices (wet elements) typified by dye-sensitized solar cells. The lifetimes of such functional devices as wet devices significantly vary depending on sealing or encapsulating techniques.
FIG. 9A shows a dye-sensitized solar cell as a wet device. The dye-sensitized solar cell 51 has an assemblage structure including a substrate 52, a transparent conductive layer (fluorine-doped tin oxide (FTO)) 53, a porous, dye-sensitized fine semiconductor particle layer 54, an electrolyte layer 56, a metal layer 57 serving as a counter electrode, a transparent conductive layer (FTO) 58, and a substrate 59 arranged in this order from a light-incoming surface.
In the wet device 51, a liquid such as an electrolyte composition 56 is charged into and encapsulated in a space between the pair of substrates 52 and 59 facing each other. In most of wet devices of this type, an outer periphery 75 of the device 51 is generally sealed with an encapsulant 60 before the charging, and a liquid is then charged into the device through a filling port (not shown) previously formed.
The encapsulant 60 is used for sealing the outer periphery 75 of the substrate 52 and 59. The encapsulant 60 generally includes a heat-sealable film, a liquid adhesive resin, or a glass frit. The substrates 52 and 59 are sealed and bonded with the encapsulant 60 by curing the encapsulant 60 while maintaining a gap between the substrates, in order to avoid a short-circuit between the electrodes.
With reference to FIG. 9B, there is proposed an organic electroluminescent (EL) device 73 including a dry device 74 having another enclosure structure (Japanese Unexamined Patent Application Publication (JP-A) No. 2004-311385).
The dry device 74 includes substrates 66 and 61 vertically facing each other. The substrate 66 includes the organic electroluminescent (EL) device 73. The device 73 contains an upper electrode 68, a hole transport layer 69, a luminescent layer 70, an electron transport layer 72, and a lower electrode 71. An outer periphery 76 of the substrates 66 and 61 is sealed with an enclosure structure. The enclosure structure includes a core 64, a metal layer 63, an adhesive layer 67, and an insulating film 65.
The enclosure structure includes a strip member and an adhesive layer 67. The strip member includes the elastic strip core 64 and the metal layer 63 covering at least part of the core 64. The enclosure structure serves to bond between the substrates 61 and 66 so as to constitute the dry device 74. The dry device 74 contains the substrates 61 and 66, and a functional device including the organic electroluminescent (EL) device 73 encapsulated between the substrates 61 and 66.